Co-pelletizing salt mixtures

• US 3,906,140 A
• Filed: 07/17/1972
• Issued: 09/16/1975
• Est. Priority Date: 08/23/1971
• Status: Expired due to Term

• Current Assignee: National Research Council Canada
• Original Assignee: Charles E. Capes
• Inventors: Capes, Charles E.
• Primary Examiner(s): Martin, William D.
• Assistant Examiner(s): Frenkel, Stuart D.
• Application Number:
  US05/272,573
• Time in Patent Office: 1,156 Days
• Field of Search: 117/1B 264/113,117,122 252/70 23/313 427/415 428/403
• US Class Current: 428/403
• CPC Class Codes: B01J 2/28 using special binding agents
• CPC Class Codes: C09K 3/185 Thawing materials
• CPC Class Codes: C09K 5/066 Cooling mixtures; De-icing compositions
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

Salts such as calcium and sodium chlorides are co-pelletized into composite pellets by contacting larger nuclei with finer particles in the presence of a salt solution which is substantially saturated in the salt of finer particle size and at least partially saturated in the other salt (or salts). This liquid acts as a viscous binder and binds the salts together into pellets in which the finer particles tend to be layered around the coarser nuclei. If desired, migration of part of the coarse nuclei salt toward the surface can be achieved. The pellets are easily handled without dusting and are useful e.g. for ice melting and dust control on roads.

Claims

1. COMPOSITE LAYERED PELLETS OF NON-UNIFORM CROSS-SECTION EACH COMPRISING A NUCLEUS INCLUDING A COARSE PARTICLE OF CALCIUM CHLORIDE, SURROUNDED BY AT LEAST ONE LAYER OF FINER PARTICLES COMPRISING SODIUM CHLORIDE, THE PARTICLES BEING BONDED TOGETHER BY SALT BRIDGES FROM A BINDER LIQUID SOLUTION OF SAID SALTS ON REMOVAL OF THE LIQUID, AND MIGRATED CALCIUM CHLORIDE HAVING FORMED INCREASED CALCIUM CHLORIDE CONTENT IN THE SURROUNDING LAYER OR LAYERS, THE CALCIUM CHLORIDE BEING PRESENT IN ABOUT 5-30% WT.

2. The pellets of claim 1 containing hydrates of CaCl2 formed from aqueous binder liquid and CaCl2 on standing at ambient temperature.

3. The pellets of claim 1 containing about 30-40% internal void space.

4. A method of forming non-uniform cross-section composite layered pellets containing calcium chloride and sodium chloride comprising:

a. providing as pellet nuclei coarse particles of calcium chloride in amounts from about 5-30% wt., b. contacting the nuclei particles with fine particles comprising sodium chloride, c. dispersing an aqueous binder liquid among the particles, the amount of binder liquid being of the order of 10-35% wt. based on dried pellet, the liquid being substantially saturated with sodium chloride and at least 40% saturated but not completely saturated with calcium chloride, d. balling the mixture with a tumbling action causing the fine particles to layer on the coarse calcium chloride, e. evaporating the aqueous liquid causing migration of some nuclei calcium chloride into surrounding layers and deposition of salt bonds, and f. recovering composite layered pellets having calcium chloride deposited among the sodium chloride.

5. The method of claim 4 wherein the fine particles are added in stages with successive layers being formed.

6. The method of claim 4, wherein the coarse salt is CaCl2 flakes from the CaCl2 recovery circuit of a Solvay process plant and the finer salt is NaCl byproduct from the same circuit.

7. The method of claim 4 wherein the binder liquid is a salt settler underflow from the CaCl2 recovery circuit of a Solvay process plant.

8. The method of claim 4, wherein the binder liquid contains about 20 to about 45% by wt. CaCl2.

9. The method of claim 4, wherein the following operation is carried out in a blanketing liquid which is immiscible with the binder liquid.

10. The method of claim 4 wherein the coarse calcium chloride is about 1-4 mm. diameter and the finer sodium chloride about 0.1-0.3 mm. diameter.

11. The method of claim 4 wherein the diameter of the coarse calcium chloride is of the ordEr of 10 times that of the sodium chloride.